Measurement of the lattice vibrations of SrTiO3 using the new detector MultiFLEXX. The compound is one of the thermoelectrical materials studied at HZB. Credit: HZB

The triple axis spectrometer FLEXX at BER II provides a new detector module for user service. It measures many angles and multiple energy transfers simultaneously and thus increases the amount of data measured per hour by about a factor of ten. This enables neutron users to make optimal use of their beam time.

Beam time at a neutron instrument is valuable – users generally have only a few days for their measurements. Often, scientists travel from other countries or even continents for an experiment. Naturally, they want to make the most of these days for their research. Therefore, an HZB team at the triple axis spectrometer FLEXX has developed the new detector module MultiFLEXX: It allows beam time to be used ten times as efficiently.

At FLEXX, magnetic excitations and lattice vibrations are measured. They typically have a characteristic relationship of excitations energy and scattering angle. One data point at FLEXX measures exactly one angle and one energy transfer, with a measurement time of several seconds up to several minutes, depending on the sample. To deduce characteristic relationships, many angles and energies need to be measured. The new detector module MultiFLEXX is able to do so with a shorter data collection time: It measures 31 angles and 5 energy transfers simultaneously, being composed of 155 analysers and detectors. Each MultiFLEXX data point has a count rate 5 to 10 times smaller than a single data point at FLEXX – thus, there is a total gain in acquisition efficiency of more than a factor of 10. This is particularly interesting for users who want to map out an excitation as a function of temperature or magnetic field – frequent applications at FLEXX.

The detector module MultiFLEXX was developed by the FLEXX team and assembled in the HZB workshops. It has already been tested successfully in several experiments, both by external users and in the HZB-internal research on thermoelectrics.